Method of making a yarn containing loops

ABSTRACT

A textured yarn is made by continuously false untwisting and reverse twisting a previously twisted and heat set continuous multi-filament thermoplastic yarn and over-feeding the yarn so that the filaments thereof can form loops. The textured yarn so produced can be plied together and twisted and then again heat set to form sewing thread.

United States Patent Bose 1 Nov. 21, 1972 [54] METHOD OF MAKING A YARN [56] References Cited 13 B H W h UNITED STATES PATENTS [72] Invent r x a mgwm 3,041,814 7/1962 Held ..57/34 3,462,933 8/1969 Nava ...57/34 [73] Assignee: English Sewing Limited, Man- 3,098,348 7/1963 Bryner ..57/157 chester, England 3,137,119 6/1964 Crouzet ..57/34 HS 3,166,881 l/l965 Servage ..'..57/34 3,318,083 5/1967 Gilchrist ..57/34 115 [2]] Appl. No.: 110,464 v Primary Examiner-Werner H. Schroeder Attorney-Cushman, Darby &- Cushman [30] Foreign Application Priority Data Feb. 7, 1970 Great Britain ..5,977/70 ABSTRACT A textured yarn is made by continuously false untwist- U.S. Cl- R ing and reverse a previously twisted and heat [5]] Int. Cl. set continuous multflfilament thermoplastic yam and Field of Search..5 7/34 HS, 77.3, 157 157 R, over-feeding the yarn so that the filaments thereof can 57/ 157 MS; 28/72 HS fonn loops. The textured yam so produced can be plied together and twisted and then again heat set to form sewing thread.

8 Claims, 1 Drawing Figure METHOD OF MAKING A YARN CONTAINING LOOPS The present invention relates to a method of manufacturing textured yarns.

Methods of making various kinds of textured yarns are well known, including those in which continuous multi-filament synthetic yarns, as for example nylon and polyester yarns, are subjected to a turbulent air stream, whereby filaments in the yarn are formed into loops. Such yarns are sold under the trade name TASLAN.

It is a feature of the present invention to make similar loop-textured filament yarns without the use of an air stream.

According to the present invention, a textured yarn containing loops is made by continuously false untwisting a substantially torque-free twisted continuous multi-filament thermoplastic yarn and over-feeding the yarn sufficiently for filaments contained in the false untwisted yarn to form loops.

The substantial freedom of the yarn from torque can be conveniently obtained by heat setting the twisted yarn.

By heat setting is meant stabilizing by heating, e.g. by dry heat or by steam, to the temperature at which stresses in the thermoplastic material, of which the filaments are made, are relieved so as to remove torque from the twisted yarn. However, there are other processes, such as chemical treatment, by which the stresses may be removed.

By over-feeding is meant allowing the yarn to contract to less than its original length.

The over-feeding should not be more than about 30 percent but for the manufacture of yarns for sewing threads it should not be more than percent and is preferably of the order of 3 percent to 5 percent. The false untwisting should preferably be at least 125 percent of the original number of turns in the twisted heat set yarn. A suitable number of turns of false untwisting is about 160 percent of the number of turns in the twisted heat set yarn.

Examples of thermoplastic yarns which may be textured by the method of the invention are nylon, polyester, cellulose acetate and cellulose triacetate.

In apparatus for carrying out the present invention, the false untwisting is carried out by means of a high speed false twisting spindle, such as is normally used in the production of false twist stretch type textured yarns, the direction of rotation of the spindle being such that the original twist in the input yarn is removed. Yarn feed rollers are preferably placed not more than six inches (15.24 cm.) from the inlet end of the false twisting spindle and yarn take-up rollers beyond the outlet end of the false twisting spindle are so coupled to the feed rollers as to be driven at a lower peripheral speed than the feed rollers.

Yarns made according to this invention may be reheat set or restabilized by again heating to the abovementioned temperature at which stresses are relieved. Sewing threads may be made from yarns made according to this invention by plying the yarns together and twisting them in the normal way and then heating them to set or stabilize them.

The invention will now be more particularly described, by way of example, with reference to the accompanying diagrammatic drawing which illustrates a yarn texturing apparatus in accordance with the invention.

Referring to the drawing, a continuous twisted multifilament thermoplastic synthetic yarn l, for example nylon or polyester, is supplied from a package 2. The twisted yarn has previously been set and stabilized by heat, e.g. by heating the package.

The yarn 1 is drawn in the direction shown by the arrows from the package 2 through a tensioner 3 by a pair of feed rollers 4, 4a and is delivered to a false twisting spindle 5. This spindle 5 is positioned close to (e.g. within 6 inches of) the feed rollers 4, 4a and the speed and direction of the spindle are such as to insert in the yarn a number of turns of false untwisting and. reverse twist equivalent to 16 percent of the number of turns in the heat set yarn 1 before treatment.

The yarn is then rewound onto a further package 6 after passing through take-up rollers 7, 7a. The rate of feed of the feed rollers 7, 7a is less than that of the feed rollers 4, 4a.

More specifically, the drawing illustrates diagrammatically one spindle of a multi-spindle false twisting machine which has been modified for carrying out the method of the present invention. The modification lies principally in that the heater which is used in conventional false twisting apparatus for setting the looped yarn is removed and instead the feed rollers 4 and 4a are placed as close as practicable to the spindle 5. One of the rollers 4, 4a is positively driven (the driving roller) whereas the other (the driven roller) is freely rotatable but is pressed against the driving roller. If necessary, the yarn can be wrapped once or twice around the driven roller to prevent slippage. The driving roller may, for example, be i inch (2.54 cm.) in diameter, whereas the driven roller is approximately one half of this diameter. The false twisting spindle 5 has no bearing but it is of very small diameter, e.g. 7/64 inch (2.8 mm.) and its periphery is held against a comparatively large diameter (e.g. 2 inch, 5cm.) driving disc by means of additional comparatively large diameter idler discs. If the driving and idler discs are magnetic then two discs in all are sufficient. Otherwise, three discs are necessary for locating the false twist spindle in position, both of these means being conventional means for supporting and driving false twist spindles. The interior of the false twist spindle may contain a bridge, eg of sapphire, around which the yarn is wrapped through one turn again in the same manner as is customarily used for false twisting. Alternatively the false twisting may be produced, for example, by frictional contact. By making the feed rollers 4, 4a of comparatively small diameter, they may be placed quite close to the spindle 5, e.g. so that the distance between the lower end of the spindle 5 and the nip between the rollers 4, 4a is about 1%inches to 2 inches (4.45 cm. to 5.08 cm.).

Since the distance between the take-up rollers 7, 7a and the false twist spindle 5 is not critical, the take-up rollers already fitted to the machine may be suitably used. One of the take-up rollers 7, 7a is positively driven (the driving roller) whilst the other (the driven roller) is freely rotatable but is pressed against the driving roller. Again, the yarn may take one or more turns around the driven roller to minimize the risk of slippage. The take-up rollers 7, 7a can, for example, each be 3 inches in diameter (7.62 cm.). The speeds of the feed rollers 4, 4a and takeup rollers '7, 7a are directly inter-related so that the peripheral velocity of the takeup rollers 7, 7a is about 96 percent of the peripheral velocity of the feed rollers 4, 4a. To avoid variations in the yarn characteristic due to speed variations, it is preferable for there to be a positive drive connection between the driving one of the feed rollers 4, 4a and the driving one of the take-up rollers 7, 7a whereby the speed relationship between the two sets of rollers remains fixed, although this speed ratio may be adjustable, for example, by employing a continuously variable speed gear box between the two driving rollers.

The package 6 onto which the yarn is wound rests under gravity against a further driven roller 8 by which the package 6 is rotated. A suitable reciprocating guide (not shown) is provided between the rollers 7,. 7a and the package 6 to ensure that the yarn is uniformly wound onto the package 6. if desired, a guide eye (not shown) may be disposed between the feed rollers 4, 4a and the spindle S to minimize or substantially prevent ballooning of the yarn.

As one example of carrying out this invention a 75 denier filament yarn is twisted to 15 turns per inch (590 turns per meter in the S-direction and this twist is then set in the yarn by subjecting the yarn package to steam in an autoclave at 28 lbs. per square inch (1.97 Kgm. per sq. cm.) pressure gauge for minutes.

The set yarn is fed through the rollers 4 at 260 ft. per minute (80.3 m. per min.). The false twist spindle 5 is rotated at 72,000 r.p.m. so that Z-direction of twist is inserted into the incoming yarn. The yarn is withdrawn by the take-up rollers 7, 7a at 250 ft. per minute (77.2 111. per min.

I claim:

Y 1. A method of making a textured yarn containing loops comprising the steps of providing a twisted continuous multi-filament thermoplastic yarn having torque stresses therein; stress-relieving said twisted yarn to substantially remove said torque stresses therefrom, continuously false untwisting said twisted stress-relieved yarn and over-feeding said false untwisted yarn sufficiently to permit loops to form in filaments in the false untwisted yarn.

2. A method according to claim 1, wherein said over feeding step comprises continuously feeding stress relieved yarn to said false twisting step at a first velocity and continuously taking up looped yarn from said false untwisting step at a second velocity lower than said first velocity by 3 to 30 percent.

3. A method according to claim 2 in which said second velocity is about 4 percent less than said first velocity.

4. A method according to claim 1 in which said false untwisting is at least percent of the number of turns in the stress-relieved twisted yarn.

5. A method according to claim 4 in which said false untwisting is about percent of the number of turns in the stress-relieved twisted yarn.

6. A method according to claim 2 in which said false untwisting is at least 125 percent of the number of turns in the stress-relieved twisted yarn.

7. A method according to claim 1 in which the thermoplastic material of the yarn is selected from the rou consistin o n ion and 01 ester. g 8. A methor? of groducing a sewing thread which comprises making a plurality of textured yarns by the method set forth in Claim 1; plying together said plurality of textured yarns; twisting the plied yarns; and heat setting the twisted plied yarns. 

1. A method of making a textured yarn containing loops comprising the steps of providing a twisted continuous multi-filament thermoplastic yarn having torque stresses therein; stress-relieving said twisted yarn to substantially remove said torque stresses therefrom, continuously false untwisting said twisted stress-relieved yarn and over-feeding said false untwisted yarn sufficiently to permit loops to form in filaments in the false untwisted yarn.
 1. A method of making a textured yarn containing loops comprising the steps of providing a twisted continuous multifilament thermoplastic yarn having torque stresses therein; stress-relieving said twisted yarn to substantially remove said torque stresses therefrom, continuously false untwisting said twisted stress-relieved yarn and over-feeding said false untwisted yarn sufficiently to permit loops to form in filaments in the false untwisted yarn.
 2. A method according to claim 1, wherein said over feeding step comprises continuously feeding stress relieved yarn to said false twisting step at a first velocity and continuously taking up looped yarn from said false untwisting step at a second velocity lower than said first velocity by 3 to 30 percent.
 3. A method according to claim 2 in which said second velocity is about 4 percent less than said first velocity.
 4. A method according to claim 1 in which said false untwisting is at least 125 percent of the number of turns in the stress-relieved twisted yarn.
 5. A method according to claim 4 in which said false untwisting is about 160 percent of the number of turns in the stress-relieved twisted yarn.
 6. A method according to claim 2 in which said false untwisting is at least 125 percent of the number of turns in the stress-relieved twisted yarn.
 7. A method according to claim 1 in which the thermoplastic material of the yarn is selected from the group consisting of nylon and polyester. 